Anacardic acid is a non-isoprenoid long chain phenolic acid primarily obtained from the nut shells of the plant Anacardium occidentale native of South America.

The solvent extracted cashewnut shell liquid (CNSL) is a rich source of many long chain phenolic compounds of which anacardic acids constitutes about 60-65% of the CNSL. The other major long chain constituents being cardol a dihydric component (15-20%) and cardanol a phenolic compound (10%).
The long aliphatic side chain of these phenolic constituents exists as a mixture of monoene, diene and triene, with the saturated component being present in negligible amount. Anacardic acids in CNSL exists as a mixture of monoene (38.4%), diene (17.4%) and triene (44.1%).
CNSL has for a long time being used as a raw material for the manufacture of polymers, paints, varnishes, brake linings etc. Apart from the industrial uses, the nut shell oil has also been used in the traditional medicine world wide for the treatment of inflammation, diarrhea, treatment of cracked foot etc.
Anacardic acid (6-pentadecyl salicylic acid) has been screened for various biological activities. It has been shown to be an inhibitor of lipoxygenase and xanthine oxidase. The antibacterial properties of anacardic acids has also been extensively studied by various groups. Kube et al studied the anti bacterial activity of the monoene (C15:1), diene (C15:2), triene(C15:3) and saturated (C15:0) anacardic acids against Stapphalococcus aureus and Methicillin resistant Stapphalococcus aureus. They have shown that the triene (C15:3) has a minimum inhibitory concentration (MIC) of 6.5 μg/mL while the saturated anacardic acid (C15:0) has a MIC of 1600 μg/mL against MRSA. They have also studied the effect of the length of the side chain on the antibacterial activity and showed that the antibacterial activity was greater as the length of the alkyl chain increased.
Though a lot of study has been done to use the naturally occurring anacardic acids as such or in combination with known antibiotics to demonstrate the antimicrobial activity, there are no reports on the synthetic modifications of anacardic acids to enhance their antimicrobial activity.
Antibiotic resistance is a very serious problem in the hospitals and is growing at a rapid pace. Resistant strains have been isolated for almost all the existing antibiotics. With the growing problem of antimicrobial resistance there is a dire need for an effective molecule to combat this problem. The objective of this invention is to enhance the antimicrobial activity of saturated anacardic acid (C15:0) especially against MRSA, by synthetic modifications.